Rectifier circuit management system, such as for use in cell site power systems

ABSTRACT

Systems, apparatus, methods, and manufactures for conserving power in a communications system such as a communications service cell site or cell site. The methods include adjusting the RF coverage of the cell site antenna, selective control of the RF output transmit power, selective control of the communications bit rate, transfer of communications to other cell sites, adjustment of indicators such that mobile devices transfer communications to other cell sites, and reallocation of logical slots between radios in the cell site. In some examples, the cell site employs a power controller. The power controller may utilize a switching circuit to produce two different voltages from a single battery string during a commercial power failure with improved conversion efficiencies. In another example, a power controller may manage multiple rectifiers so that the rectifiers operate more efficiently, such as with approximately equal runtime and with regular testing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/855,667, filed Apr. 2, 2013, now U.S. Pat. No. 8,983,546,entitled “RECTIFIER CIRCUIT MANAGEMENT SYSTEM, SUCH AS FOR USE IN CELLSITE POWER SYSTEMS”, which is a division of U.S. patent application Ser.No. 12/726,279, filed Mar. 17, 2010, now U.S. Pat. No. 8,412,272,entitled “RECTIFIER CIRCUIT MANAGEMENT SYSTEM, SUCH AS FOR USE IN CELLSITE POWER SYSTEMS”, which claims priority to U.S. Provisional PatentApplication No. 61/228,467 entitled “CELL SITE IMPROVEMENTS,” filed onJul. 24, 2009, which is hereby incorporated by reference herein.

BACKGROUND

The popularity of commercial wireless communications services (e.g.,wireless telephony, wireless network access, and wireless email) hassubstantially increased during recent years. In many cases, users, suchas consumers, mobile workers, emergency response personnel, and/or thelike, now utilize these services for both personal and businesscommunications. Likewise, users are increasingly relying on theseservices. For example, some households forgo wired telephone service infavor of wireless telephone service; some government agencies rely onthese services for both routine and emergency communications; andbusinesses rely on these services to communicate with customers andmobile workers. Correspondingly, the cost (both financial andnonfinancial) of outages is also increasing.

Typical commercial wireless communications service (“CMRS”) providersrely on remote facilities to provide services. For instance, CMRSproviders rely on cell sites (e.g., base stations, radio repeaters,wireless to back-haul interfaces, etc.) to facilitate somecommunications services. If a cell site experiences a loss ofcommercially provided electrical power, users near the cell site mayexperience a service outage. Power outages are an example of a commoncause for cell site failures. For example, natural disasters, rollingbrownouts, accidents, and/or the like may result in power outages. Whilemost cell sites include some form of backup power (e.g., generatorsand/or batteries), these forms of backup power may not providesufficient power during lengthy power outages and may require servicing,monitoring, and on-site maintenance. During lengthy power outages, theuse of commercial wireless communications services may increase due tousers' needs and/or desires. Further, pending regulations may requirecommercial wireless communications service providers to provide cellsites with at least seven days of back-up power.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an environment for practicing theinvention;

FIG. 2 is a diagram of another suitable environment for practicing theinvention;

FIG. 3 is a block diagram of a communications system usable in theenvironments of FIGS. 1 and 2;

FIG. 4 is a logical diagram of a radio shelf usable in the base stationof FIG. 3;

FIG. 5 is a logical flow diagram of a process for conserving power in acommunications system;

FIG. 6 is a block diagram of a suitable cell site for use in theenvironment of FIG. 1;

FIG. 7 is a block diagram of a suitable power controller usable in thecell site of FIG. 6;

FIG. 8 is a schematic diagram of a suitable rectifier and switch circuitusable in the cell site of FIG. 6; and

FIG. 9 is a logical flow diagram of a suitable process for managing arectifier and switch circuit having multiple rectifiers.

DETAILED DESCRIPTION

The following description provides specific details for a thoroughunderstanding of, and enabling description for, various embodiments ofthe technology. One skilled in the art will understand that thetechnology may be practiced without many of these details. In someinstances, well-known structures and functions have not been shown ordescribed in detail to avoid unnecessarily obscuring the description ofthe embodiments of the technology. The terminology used in the belowdescription should be interpreted in its broadest reasonable manner,even though it is being used in conjunction with a detailed descriptionof certain embodiments of the technology. Although certain terms may beemphasized below, any terminology intended to be interpreted in anyrestricted manner will be overtly and specifically defined as such inthis Detailed Description section.

As one non-limiting example, the technology may be employed forconserving power in a communications system such as a wirelesscommunications service cell site. For example, the technology may beemployed to conserve power during a power source's periods of reducedavailability. A cell site's run time from backup power may be increasedby employing the various power conservation features described below.For example, the cell site may decrease the backup battery circuitdischarge rate, the backup generator fuel consumption rate, and/or thelike.

As another non-limiting example, a cell site may include a powercontroller that utilizes a switching circuit (e.g., an H-bridge) toproduce two different voltages from a single battery string during acommercial power failure with improved conversion efficiencies. The dualvoltages produced may permit a cell site to utilize legacy andnext-generation wireless protocols during a power failure.

As another non-limiting example, a cell site power controller mayprovide management of multiple rectifiers. The power controller mayrotate the rectifiers in and out of active operation so that therectifiers operate closer to capacity and, thus, more efficiently.Rectifier rotation also ensures that the runtime of the variousrectifiers is approximately equal and provides a way of testing therectifiers for failures.

The below described power conservation features may also decrease bothcapital and operating costs for providing backup power to a cell site.For example, pending Federal Communications Commissions (“FCC”)regulations may require commercial wireless communications serviceproviders to provide cell sites with at least seven days of backuppower. Likewise, Environmental Protection Agency (“EPA”), state, andlocal regulations may regulate storage of large amounts of backupgenerator fuel. In addition, the cost, size, and weight of backupbatteries may limit the number of batteries that can be practicallylocated at a cell site. For these and other reasons, the powerconservation features described below may be employed to increase thebackup power runtime for cell sites.

Suitable System

FIG. 1 is a block diagram of an environment 190 in which the inventionmay be practiced. As shown, the environment 190 includes a cell site 100configured to wirelessly communicate with wireless devices 197-199. Thecell site 100 includes an antenna 192, and a remote tilt mechanism 130.The cell site 100 is coupled to a back-haul 194 and configured toreceive power via a primary power signal PRI_IN and an alternate powersignal ALT_IN.

The cell site 100 may include virtually any device for facilitatingwireless network access. For example, the cell site 100 may be awireless telephony base station, a wireless network access base station,a wireless email base station, and/or the like. In one embodiment, thecell site 100 is operated by a mobile telephony service provider orCMRS. Generally, the cell site 100 is configured to provide a networkinterface for wireless devices 197-199 by providing an interface (viathe antenna 192) between wireless devices 197-199 and the back-haul 194.The cell site 100 and wireless devices 197-199 may communicate using anywireless protocol or standard. These include, for example, Global Systemfor Mobile Communications (“GSM”), Time Division Multiple Access(“TDMA”), Code Division Multiple Access (“CDMA”), Orthogonal FrequencyDivision Multiple Access (“OFDM”), General Packet Radio Service(“GPRS”), Enhanced Data GSM Environment (“EDGE”), Advanced Mobile PhoneSystem (“AMPS”), Worldwide Interoperability for Microwave Access(“WiMAX”), Universal Mobile Telecommunications System (“UMTS”),Evolution-Data Optimized (“EVDO”), Long-Term Evolution (“LTE”), UltraMobile Broadband (“UMB”), and the like.

The back-haul 194 may be any connection that provides a networkinterface for the cell site 100. For example, the back-haul 194 mayinclude one or more T-1 connections, T-3 connections, OC-3 connections,frame relay connections, Asynchronous Transfer Mode (ATM) connections,microwave connections, Ethernet connections, and/or the like. Inaddition, the back-haul 194 may provide an interface to a telephoneswitch (e.g., to a 9ESS switch or a Private Branch Exchange switch), toa data network (e.g., to a router or network switch), and the like.

The cell site 100 may also be configured to receive power via theprimary power signal PRI_IN, for example, as alternating current (“AC”)power from a public utility, a power grid, photovoltaic power sources(e.g., solar panels or arrays), a turbine, a fuel cell, a generator,and/or the like. However, the primary power signal PRI_IN may beprovided by virtually any power source and as either AC and/or directcurrent (“DC”) power.

Further, the cell site 100 may also be configured to receive power viaalternate power signal ALT_IN, for example, from an alternate energypower source. Alternative energy sources may include photovoltaic powersources, wind power sources, geothermal power sources, generators, fuelcells, bioreactors, and/or the like. In typical environments, DC poweris received by the cell site 100 via alternate power signal ALT_IN.However, either AC and/or DC power may be received via alternate powersignal ALT_IN.

At times, however, primary power signal PRI_IN and/or alternate powersignal ALT_IN may provide insufficient power to operate the cell site100 (e.g., during a commercial power outage). Accordingly, the cell site100 may also include a battery circuit, as discussed below. While thecell site 100 may include backup power sources, it may be beneficial toconserve power at the cell site 100 during such reduced availabilityperiods. Such power conservation may increase the backup power runtimeof the cell site 100.

The remote tilt mechanism 130 may be included to control a tilt angle ofthe antenna 192. The tilt angle of the antenna 192 may, for example,define a radio frequency (“RF”) coverage (e.g., coverage area,footprint, pattern, etc.) of the cell site 100. The remote tiltmechanism 130 may include an electronically controlled actuator such asa solenoid, motor, and/or the like and may be configured to tilt theantenna 192 based, at least in part, on a tilt signal TILT.

The antenna 192 may be included to facilitate communications betweenmobile devices 197-199 and the cell site 100 and is coupled to the cellsite 100 via antenna signal ANT. Antenna 192 may be any type of suitableantenna. One example of a suitable antenna includes a directional flatpanel antenna having fixed gain and fixed azimuth angle. However, othertypes of antennas may also be suitably employed. For example,omnidirectional antennas, lossy transmission lines, beam steerableantennas, variable gain antennas, and/or the like may be employed asappropriate. The antenna 192 may also include a preamplifier (not shown)to preamplify received signals. The cell site 100 may be coupled to anynumber of antennas. For example, a typical cell site may providecoverage to three sectors of approximately 120° each. One or moreantennas may provide coverage to each sector. However, in other systems,any other number of antennas and/or sectors may be employed. Also, theantenna 192 may be either a tiltable or a non-tiltable antenna.

The remote tilt mechanism 130 may be omitted in some environments. Forexample, the remote tilt mechanism 130 may be omitted if the antenna 192is an omnidirectional antenna, a beam steerable antenna, and/or thelike.

Wireless devices 197-199 may include virtually any devices forcommunicating over a wireless network. For example, wireless devices197-199 may include mobile telephones (e.g., cellular telephones, GSMtelephones, TDMA telephones, LTE telephones, etc.), wireless datadevices (e.g., Personal Digital Assistants (PDAs), computers, pagers,etc.), and/or the like.

Table 1, below, introduces various power conservation features that maybe employed in the cell site 100 and/or in the environment 190 toselectively conserve power. These power conservation features aredescribed in greater detail below.

TABLE 1 power conservation features. 1 selective adjustment of the RFcoverage of the antenna 192 2 selective control of an RF output transmitpower level 3 selective control of a communications bit rate 4 transferof communications to other cell sites 5 adjustment of indicators suchthat associated mobile devices transfer communications to other cellsites 6 reallocation of communications between radios and logical slotsof the cell site 100 7 utilization of a switching circuit to producedual output voltages from a single battery string 8 management ofmultiple rectifiers to improve efficiency and rectifier testing

In addition, the various power conservation features of Table 1 may alsobe employed in conjunction with the fuel conservation and othertechnologies described in the assignee's U.S. patent application Ser.No. 12/170,675, entitled “CELL SITE POWER GENERATION,” filed on Jul. 10,6008, which is hereby incorporated by reference.

These other power conservation features may be selectively enabledbased, at least in part, on power source availability. The various powerconservation features may also be selectively enabled based, at least inpart, on other environmental parameters. For example, environmentalparameters may include the amount of RF interference, the distancebetween the cell site 100 and wireless devices 197-199, topography,geography, and/or the like.

As one example, the RF interference may be quantified through a carrierto interference ratio (“C/I”). However, in other examples, a signal tonoise ratio (“SNR”), a bit error rate (“BER”), a frame error rate(“FER”), and/or the like may also be suitably employed. In addition,resource management (e.g., base station traffic load, system trafficload, etc.) and aggregate call quality may be factors to determinewhich, if any, power conservation features are employed with eachparticular wireless device or communications channel. For example, whilethe cell site 100 communicates with a wireless device over a favorableC/I channel (e.g., greater than 20 dB), more power conservation featuresmay be employed. However, if the channel between the cell site 100 andanother wireless device has a less favorable C/I (e.g., less than 9 dB),fewer power conservation features may be employed. In this way, the cellsite 100 may balance power consumption and call quality considerations.Also, the various power conservation features may be individually orcollectively employed in any number of combinations. For example,multiple or all of the power conservation features of Table 1 may besimultaneously employed during certain conditions such as during anextended power outage, when backup power is low, when call volume ishigh, and/or the like.

The cell site 100 may be configured to selectively tilt the antenna 192to selectively define, in part, its RF coverage. For example, changingthe RF coverage of the antenna 192 may affect power consumption byincreasing or decreasing the number of wireless devices associated withthe cell site 100. Selective tilting of the antenna 192 is discussed infurther detail with respect to FIG. 2.

The cell site 100 may be further configured to selectively control itsRF output transmit power. For example, the cell site 100 may selectivelydecrease its RF output transmit power as a power conservation feature orincrease its RF output transmit power to increase its RF coverage. Thisselective control may include changing the RF output transmit power byany suitable amount. As one example, the cell site 100 may be configuredto increase or decrease its RF output transmit power in 2 decibel (“dB”)steps.

Additionally, the cell site 100 may be configured to selectively controla communications bit rate for voice traffic. For example, the cell site100 may decrease its voice traffic communications bit rate whileoperating from backup power and increase its bit rate while operatingfrom a commercial power source. By lowering the communications bit rate,the cell site 100 may process a given amount of voice traffic whileemploying fewer radios and/or logical slots. Unused radios and/orlogical slots may be disabled to conserve power.

As one example, a suitable bit rate may be configured by selectingbetween codecs such as a full-rate codec, an enhanced full-rate codec, ahalf-rate codec, various modes of an adaptive multi-rate codec, and/orthe like. Selection between these codecs may affect both the compressionfor the voice traffic and the bit-rate of additional information that istransmitted with the compressed voice traffic. This additionalinformation may include padding, forward error correction coding, othererror coding, and/or the like. In addition, discontinuous transmission(“DTX”) thresholds and/or the like may also be adjusted based, at leastin part, on the power source availability status. Adjustment of DTXthresholds may further affect the communications bit rate.

In addition, the communications bit rate may also be selectivelycontrolled based, at least in part, on environmental parameters. Forexample, a codec and/or bit rate may be selected based, at least inpart, on the C/I of a particular logical slot. This codec and/orbit-rate may then be adjusted based, at least in part, on the powersource availability status. For example, during a commercial powersource outage, a bit-rate that is one or two steps lower than wouldotherwise be employed for the given C/I level may be employed as a powerconservation feature.

The cell site 100 may also be configured to transfer voice and/or datatraffic from wireless devices 197-199 to another cell site. For example,the cell site 100 may employ directed retries, forced handoffs, and/orthe like. By decreasing communications, the cell site 100 may decreasethe number of radios in operation, the number of active logical slots,the amount of voice traffic, and/or the like. In turn, this may reducepower consumption at the cell site 100.

Likewise, the cell site 100 may be configured to adjust indicators suchthat wireless devices transfer communications to other cell sites, suchas adjacent and/or neighboring cell sites. As one example, the cell site100 provides indicators to wireless devices 197-199 to indicate anestimated or calculated service level for communications with both thecell site 100 and other cell sites. These indicators may represent asignal level (e.g., RSSI, C/I, BER, FER, etc.) received from wirelessdevices 197-199 at each cell site within a geographical area. Theseindicators may also be based, at least in part, on a cell 1 reselect(“C1”) value or a cell 2 reselect (“C2”) value from a base stationcontroller such as a base station controller 350 shown in FIG. 3.

Wireless devices 197-199 may then employ these indicators to requestassociation with a particular cell site. The cell site 100 and/or anassociated component (e.g., a system controller 320, an OMC 330, aswitch 340, a base station controller 350, or an RNC 360 of FIG. 3) mayadjust these indicators to offset the indicated levels from theestimated or calculated values. For example, the cell site 100 and/orthe associated component may adjust the C1 or C2 values and/or areceiver access minimum value such that wireless devices 197-199 may beinduced to prefer and/or transfer association with, or to, an adjacentor neighboring cell site operating from a commercial power source.

In addition, the cell site 100 may reallocate communications betweenradios and logical slots of the cell site 100 based, at least in part,on the commercial power source outage status. For example, the cell site100 may employ different radios and/or logical slots to facilitatecommunications between the cell site 100 and wireless devices 197-199.Reallocation of logical slots is discussed in further detail withrespect to FIG. 4.

In addition, the cell site 100 may comprise a power controller (e.g.,610 in FIG. 6) that utilizes a switching circuit (e.g., a doublingswitching circuit, an H-bridge, etc.) to produce two different voltagesfrom a single battery string during a commercial power failure withimproved conversion efficiencies. The dual voltages may permit the cellsite 100 to utilize both legacy and next-generation wireless protocolseven during a power failure. The utilization of a doubling switchingcircuit is discussed in further detail with respect to FIG. 6.

In addition, the cell site 100 may comprise a power controller thatprovides management of multiple rectifiers. The power controller rotatesthe rectifiers in and out of active operation so that the rectifiersoperate closer to capacity and thus, more efficiently. The rotation alsoensures that the runtime of the various rectifiers is approximatelyequal and provides a way of testing the rectifiers for failures. Themanagement of multiple rectifiers is discussed in further detail withrespect to FIGS. 6-9.

As one example, the cell site 100 draws approximately 39 amperes ofcurrent (at approximately −56 volts) while operating at full power. Byenabling a half-rate codec instead of a full-rate codec, the currentdraw decreases to approximately 31 amperes. By additionally decreasingthe transmitter output power by 2 dB, the current draw decreases toapproximately 27 amperes. By additionally decreasing the transmitteroutput power by another 2 dB, the current draw decreases toapproximately 24 amperes. In this example, a commercial wirelesscommunications service provider may prefer the 27 ampere consumptionlevel as a balance between power consumption and system performance.

One skilled in the art will appreciate that although illustrated in thecontext of a wireless telecommunications environment, the invention maybe practiced in any environment in which backup power serves acommercial, public, or private operation or system reliant uponelectrical power.

FIG. 2 is a diagram of an environment 290 in which power conservationfeatures may be practiced. As shown, the environment 290 includes a cellsite 200, a remote tilt mechanism 130, and an antenna 192. FIG. 2illustrates the relationship between an elevation difference angle 210,a location 220, and a location 230. FIG. 2 is not drawn to scale.

As discussed above, the cell site 200 may be configured to selectivelytilt the antenna 192 to define, in part, its RF coverage. As shown inFIG. 2, the tilt angle of the antenna 192 defines, in part, thecommunications range of the cell site 200. For example, if set at afirst angle while the cell site 200 provides a constant RF outputtransmit power, the communications range may reach the location 220.However, if the antenna 192 is up-tilted by the elevation differenceangle 210, the communications range may be extended to the location 230for the same RF output transmit power. While the C/I for communicationswith the cell site 200 may decrease, up-tilting the antenna 192 may beemployed with corresponding RF output transmit power decreases tomaintain a coverage area while conserving power. Tilting of the antenna192 may be accomplished either by mechanically tilting the antenna 192or by beam steering the elevation angle of the antenna 192.

As one example of a communication system, the antenna 192 may beup-tilted by approximately 4° during normal operation. During acommercial power source outage, the antenna 192 may be up-tilted by anelevation difference angle 210 of approximately 2° (to approximately 6°)while the RF output transmit power is reduced by 2 dB. In addition,during an extended commercial power source outage, the antenna 192 maybe up-tilted by two times the elevation difference angle 210 (toapproximately 8°) while the RF output transmit power is reduced by anadditional 2 dB. However, any other suitable elevation difference anglesand/or RF output transmit power reductions may be employed.

However, the elevation difference angles discussed herein are merelyprovided as an example of elevation difference angles in one system.Such elevation difference angles may depend on a vertical beam width, anazimuth angle, environmental conditions, and/or the like for aparticular system and/or antenna. Other elevation difference angles maybe employed to provide and/or maintain coverage in a geographical area.Likewise, elevation difference angles may be selected to adjust ahandoff point at which a wireless device may handoff from the cell site200 to an adjacent or neighboring cell site.

Illustrative Communications System

FIG. 3 is a block diagram of a communications system 390. Thecommunications system 390 includes cell site 200, remote tilt mechanism130, antenna 192, system controller 320, an operations and maintenancecenter (“OMC”) 330, switch 340, base station controller 350, and RNC360. Cell site 200 includes base station 312, Node-B 314, commercialpower interface 315, back-up power circuit 316, and antenna interface319. The backup power circuit 316 includes battery circuit 317 andback-up generator 318. The communications system 390 is illustrated as aGSM/UMTS communications system, however, the invention is not limited toGSM/UMTS communications systems. For example, the invention may also bepracticed in an LTE and/or other fourth generation wireless environment.

The system controller 320 may be provided to control the communicationssystem 390. For example, the system controller 320 may be a computersystem programmed to control a core communications system, such as allor part of the communications system in a metropolitan market, aregional communications system, a commercial wireless communicationsservice provider's entire network, etc. The system controller 320 mayalso be an interface for manually controlling the operations of a corecommunications system or the like. As one example, the system controller320 is a computer system programmed to execute control scripts (e.g.,Perl scripts, Tcl scripts, Python scripts, Ruby scripts, LabVIEWscripts, etc.) to control the OMC 330 and/or other elements. Likewise, asingle system controller 320 may be employed to control multiple OMCs.

As illustrated, the OMC 330 is coupled to the system controller 320, theswitch 340, the base station controller 350, the RNC 360, and the cellsite 200. The OMC 330 may also be configured to provide a centralizedplatform from which a commercial wireless communications serviceprovider may monitor and control operational aspects of the elements ofthe communications system 390. The OMC 330 may enable the control ofboth radio elements and switching elements of the communications system390. The OMC 330 may be configured to manage any number of switches,base station controllers, RNCs, and cell sites.

The switch 340 may be coupled to the OMC 330, the base stationcontroller 350, and the RNC 360. For example, the switch 340 may beconfigured to switch voice traffic from one or more base stationcontrollers to a public switched telephone network (PTSN) or to atelephone switch such as a 5ESS switch, a Private Branch Exchangeswitch, and/or the like via signal VOICE. Likewise, the switch 340 maybe further configured to switch data from one or more RNCs to a datanetwork, to a router, to a switch, and/or the like via signal DATA.Also, the switch 340 may include a mobile switching center (MSC), amedia gateway, a call gateway, and/or the like.

The base station controller 350 may be coupled between the switch 340and the cell site 200 to control certain operational aspects of the basestation 312 of the cell site 200. For example, the base stationcontroller 350 may be configured to control handoffs, networkregistration for mobile devices, channel allocation, radio transmitteroutput power, and/or the like. Likewise, the base station controller 350may be configured to adjust a C1 value based, at least in part, oncontrol from the system controller 320 or the OMC 330. The base stationcontroller 350 may be employed to control any number of base stations.

The RNC 360 may be coupled between the switch 340 and the cell site 200to control certain operational aspects of the Node-B 314 of the cellsite 200. Also, the RNC 360 may be employed to control any number ofNode-Bs. As an example, the RNC 360 may be a UMTS counterpart of thebase station controller 350.

As stated above, the cell site 200 may include base station 312, Node-B314, commercial power interface 315, the backup power circuit 316, andantenna interface 319. The backup power circuit 316 may include thebattery circuit 317 and the backup generator 318. In typicalcommunications systems, the base station 312 and the Node-B 314 areconfigured to provide a low-level radio interface to wireless devicesunder the control of the base station controller 350 and the RNC 360.For example, the base station 312 may provide low-level GSM radiointerfacing while the Node-B 314 provides low-level UMTS radiointerfacing. Also, the cell site 200 may include limited command andcontrol functionality or no command and control functionality. Instead,the base station controller 350 and/or the RNC 360 may provide suchfunctionality while the cell site 200 merely provides a physical layerinterface to associated mobile devices. Node-B 314 may also beconfigured to provide tilt signal TILT to remote tilt mechanism 130.

The commercial power interface 315 may receive power from a commercialpower source via line PRI_PWR and provide the received commercial powerto the base station 312, the Node-B 314, and the backup power circuit316. The backup power circuit 316 may receive power from the commercialpower interface 315 to charge/recharge the battery circuit 316, and thebackup power circuit 316 may provide power to the base station 312 andthe Node-B 314 during a power source's periods of reduced availability.

The cell site 200 may also include the antenna interface 319 to providea physical interface between the base station 312, the Node-B 314, andthe antenna 192. For example, the antenna interface 319 may be a smartbias tee that is configured to physically interface the RF signalsbetween the base station 312, the Node-B 314, and the antenna 192. Asmart bias tee may be further adapted to provide power to a receiverpreamplifier in the antenna 192.

In other examples, the antenna interface 319 may include duplexers,diplexers, multiplexers, and/or the like. Also, the antenna interface319 may be omitted in certain cell sites. For example, the base station312 may be configured to receive RF signals from the Node-B 314, and tocouple these and other RF signals to the antenna 192.

In operation, the communications system 390 is configured to enable anddisable various power conservation features at the cell site 200 based,at least in part, on a power source availability status, as discussedabove. As one example, power conservation features may be enabled anddisabled by the system controller 320 or the OMC 330. However, in othercommunications systems, power conservation features may also becontrolled by the switch 340, the base station controller 350, the RNC360, or within the cell site 200. Likewise, tilt signal TILT may beprovided to the remote tilt mechanism 130 from a suitably equipped basestation 312 and/or the like.

Illustrative Logical Diagram

FIG. 4 is a logical diagram of a radio shelf 400 usable in the basestation 312 of FIG. 3. As shown, the radio shelf 400 includes radiosRADIO1-RADIO5. Each of radios RADIO1-RADIO5 includes logical slotsSLOT1-SLOT8.

As discussed above, the cell site 200 may be configured to reallocatecommunications between radios and logical slots of the cell site 200based, at least in part, on a power source availability status and onenvironmental parameters.

As one example, RADIO1 is a broadcast control channel (“BCCH”) radiothat is configured to broadcast base station identification,synchronization data, control information, other data, and/or the like,over one or more BCCH logical slots. In a typical system, these BCCHslots are broadcast at full power to provide increased visibility of thecell site 200 throughout its service area. Accordingly, other logicalslots of the BCCH radio and/or near the BCCH slot may experienceincreased interference due to adjacent channel interference,inter-symbol interference, and/or the like.

In one system, SLOT1-SLOT4 of RADIO1 are employed to transmit BCCH datawhile SLOT5-SLOT8 of RADIO 1 are left unused, or employed to transmitlower priority traffic. Lower priority traffic may include traffic thatdoes not substantially benefit from low latency transmission and mayinclude Short Message Service (SMS) messages, wireless data, and/or thelike. For example, such allocation may improve C/I for other logicalslots allocated to higher priority voice traffic. Also, radios andlogical slots allocated to voice traffic may employ RF output transmitpower control on a per connection (e.g., voice call) or per logical slotbasis to increase the C/I for other logical slots.

However, during a period of reduced power source availability, thebenefits of increased C/I may be outweighed by power conservationrequirements. Accordingly, voice traffic may be transmitted from theBCCH radio to reduce the number of operating radios. Likewise, thebit-rate of voice traffic may also be decreased to “pack” additionalvoice calls onto the BCCH radio. For example, SLOT5-SLOT8 of RADIO1 maybe employed to enable 8 half-rate voice calls.

Illustrative Logical Flow Diagram

FIG. 5 is a logical flow diagram of a process 500 for conserving powerin a communications system. For clarity, the process 500 is describedbelow as being performed by particular elements of the communicationssystem 390 of FIG. 3. However, the process 500 may also be, for example,performed by other processors, by other elements, or in other systemswhether such processors, elements, or systems are described herein. Inaddition, the process 500 may be stored in non-volatile memory.

Flowing from a start block, processing begins at step 510 where the cellsite 200 disables power conservation features. For example, the systemcontroller 320, the OMC 330, the switch 340, the base station controller350, and/or the RNC 360 may instruct the cell site 200 to disable powerconservation features. As discussed above, the cell site 200 may operatewith power conservation features disabled to increase call qualityand/or the like, while the cell site 200 is powered from a commercialpower source. In addition, the OMC 330 or the system controller 320 mayalso clear alarms at step 510.

At decision block 520, the cell site 200 determines the availability ofa power source. Also, the cell site 200 may transmit an alarm to the OMC330, report reduced availability to the system controller 320, and/orthe like. The cell site 200 may transmit the alarm, signal, or report onbackend interface 120, on an over-the-air interface, and/or the like.Within the cell site 200, the base station 312 may determine the powersource availability. However, in other cell sites, the Node-B 314 and/orother elements may determine the power source availability status. Ifthe cell site 200 determines that there is reduced power sourceavailability, processing flows to decision block 530. Otherwise,processing stays at decision block 520.

At decision block 530, the system controller 320 or the OMC 330determines if a first condition is met. Table 2, below, includes someexample of possible conditions.

TABLE 2 power conservation conditions. 1 a duration of reduced powersource availability (e.g., zero minutes, 10 minutes, etc.) 2 thequantity (e.g., number or percentage) of cell sites, sectors, radios,and/or the like experiencing reduced power source availability 3 astatus of a backup power supply 4 the load (e.g., number of connectedcalls, amount of data traffic, volume of communications, etc.) on thecell site

The system controller 320 or the OMC 330 may monitor these and otherconditions. If the system controller 320 or the OMC 330 determines thatthe first condition is met, it moves processing to step 540. Otherwise,it returns processing to decision block 520.

In one system, the system controller 320 moves processing to step 540after the cell site 200 has operated from backup power for 10 minutes,after a voltage of the backup power supply changes to −54 volts, whenfive cell sites or 10% of cell sites in a geographical area experiencereduced power source availability, and/or the like. In another system,the system controller 320 moves processing to step 540 after the cellsite 200 has operated from backup power for 15 minutes. Such a delaytime may be employed to confirm and/or ensure that reduced power sourceavailability is due to, for example, a power outage. However, any othersuitable thresholds and/or conditions may be employed.

At step 540, the cell site 200 enables a first set of power conservationfeatures. As one example, the system controller 320 may transfer trafficto the BCCH radio. In another example, the system controller 320 mayalternately or additionally up-tilt the antenna 192 by approximately 2°while reducing the RF output transmit power by 2 dB. In yet anotherexample, a cell site without an electrically tiltable antenna may employother power conservation. For example, a cell site may reduce thetransmit power for the BCCH radio by 2 dB while adjusting a C1 valueand/or a receiver access minimum value to maintain the communicationsrange of the cell site while conserving power. Processing continues atdecision block 550.

Conditions may be selected from Table 2 and corresponding powerconservation factors may be selected from Table 1 by a networkadministrator, defined in a configuration or script file, dynamicallydetermined via machine learning (e.g., artificial intelligence), and/orthe like.

At decision block 550, the cell site 200 determines if there is reducedpower source availability (e.g., an outage has not ended). As discussedabove, this determination may, for example, be made by the base station312 or the Node-B 314. If the cell site 200 determines that there isreduced power source availability, processing flows to decision block560. Otherwise, processing flows to step 510. Some or all of the powerconservation features may also remain enabled for a period of time afterthe cell site 200 detects the end of the reduced power sourceavailability. Such a delay may be employed to confirm and/or ensure thatthe power source is providing stable power, to provide additionalcharging current to a backup battery circuit, and/or the like. In onesystem, a delay of 30 minutes is employed before processing flows tostep 510. However, no delay, or any other suitable delay, may beemployed in other systems.

At decision block 560, the cell site 200 determines if a secondcondition has been met. As discussed above, this determination may, forexample, be made by the base station 312 or the Node-B 314. The secondcondition may include conditions discussed above with regard to decisionblock 530 and Table 2. The system controller 320 or the OMC 330 may beemployed to determine if the second condition is met and may employdifferent thresholds, combinations of conditions, and/or the like todetermine if the second condition is met. If the system controller 320or the OMC 330 determines that the second condition is met, it movesprocessing to step 570. Otherwise, it returns processing to decisionblock 550.

In one system, the system controller 320 moves processing to step 540after the cell site 200 has operated from backup power for 20 minutes,after the voltage of the backup power supply changes to −52 volts, whenseven cell sites or 5% of cell sites in a geographical area experiencereduced power source availability, and/or the like. However, any othersuitable thresholds and/or conditions may be employed.

At step 570, the cell site 200 enables a second set of powerconservation features. Step 570 may include enabling additional powerconservation features or may include changing parameters of the firstset of power conservation features to further increase powerconservation, such as those selected from Table 1, above.

As one example, the system controller 320 may transfer traffic to theBCCH radio, up-tilt the antenna 192 by approximately 4°, and reduce theRF output transmit power 4 dB. Processing continues at decision block550. Such a change can reduce the total power consumption of a 15transceiver cell site from approximately 40 amperes to approximately 27amperes as approximately a 32% decrease in power consumption whilemaintaining the cell site's coverage area. As discussed above, any othersuitable elevation difference angles may be employed.

Processing then continues at decision block 580 where the cell site 200determines if there is reduced power source availability (e.g., anoutage has not ended). If the cell site 200 determines that there isreduced power source availability, processing remains at decision block580. Otherwise, processing returns to block 510. As discussed above,some or all power conservation features may remain enabled for a periodof time after cell site 200 detects the end of the reduced power sourceavailability.

Illustrative Cell Site System

FIG. 6 is a block diagram of a portion of a cell site 600. The cell site600 includes a power controller 610, a rectifier and switch circuit 630,a primary power interface 640, an alternate power interface 650, abattery circuit 660, and a communications interface 680. The cell site600 may be employed as an embodiment of the cell site 100 of FIG. 1.

The power controller 610 is configured to control the power systems ofthe cell site 600. As illustrated, the power controller 610 isconfigured to receive or provide control signals 612, to receive statussignals COM_STAT, RECT_STAT, and BAT_STAT, and to provide output/controlsignals RECT_CTL, BAT_CTL, and STATUS, as discussed below.

The power controller 610 is configured to manage and control theoperation of the rectifier and switch circuit 630 and the batterycircuit 660 based, at least in part, on the various status andoutput/control signal inputs. For example, when a primary power signalis available to the system, the power controller 610 may utilizeoutput/control signals RECT_CTL and BAT_CTL to coordinate the chargingand/or testing of the battery circuit 660. When primary power signalPRI_IN and/or alternate power signal ALT_IN fails (e.g., during a poweroutage), the power controller 610 may utilize output/control signalsRECT_CTL and BAT_CTL to route battery power from the battery circuit 660to the communications interface 660 and/or the power controller 610. Asanother example, the power controller 610 may, in accordance with anapplicable rotation policy (described herein), utilize output/controlsignals RECT_CTL to rotate which rectifiers are in active, onlineoperation within the rectifier and switch circuit 630. The operation ofthe power controller 610 is discussed in further detail with regard toFIG. 7.

The rectifier and switch circuit 630 is configured to selectively routepower between and/or among the primary power interface 640, thealternate power interface 650, the battery circuit 660, thecommunications interface 680, and the power controller 610. For example,the rectifier and switch circuit 630 may be configured to selectivelypower the communications interface 680 from one or more of the primarypower interface 640, the alternate power interface 650, and/or thebattery circuit 660. In addition, the rectifier and switch circuit 630may be further configured to route operational power to the powercontroller 610 (power connection line not shown).

The power controller 610 may control the rectification, switching,charging, and other operations of the rectifier and switch circuit 630via output/control signals RECT_CTL. The rectifier and switch circuit630 may be configured to provide the status signals RECT_STAT to thepower controller 610, for example, to indicate the status of rectifiers,inverters, chargers, switches, power source outputs, failure conditions(e.g., rectifier failure, inverter failure, switch failure, excessivecurrent draw, out of range inputs/outputs, etc.), and/or the like. Asone example, the status signals RECT_STAT may provide an indication ofthe various output currents produced by one or more rectifiers in therectifier and switch circuit 630. The status signals RECT_STAT may beprovided to the power controller 610 to enable the power controller 610to adjust the operation of the rectifier and switch circuit 630 based onthese and other conditions such as the status of the primary powersignal PRI_IN, temperatures in the cell site 100, the status of thealternate power signal ALT_IN, and/or the like.

The rectifier and switch circuit 630 may include switching devices ofany type (e.g., field-effect transistors, insulated gate bipolartransistors, junction field-effect transistors, bipolar-junctiontransistors, relays, transmission gates, etc.) that are configured toselectively switch (e.g., route) power among the elements of the cellsite 600. In addition, the rectifier and switch circuit 630 may alsoinclude one or more rectifiers configured to rectify AC power from theprimary power interface 640 and/or the alternate power interface 650 toprovide DC power to the communications interface 680, the batterycircuit 660, and/or the power controller 610.

Further, rectifiers, switches, and/or other circuitry of the rectifierand switch circuit 630 may be configured to selectively charge thebattery circuit 660 from the primary power interface 640 and/or thealternate power interface 650. For example, the rectifier and switchcircuit 630 may include and/or be configured as a trickle charger, aconstant current charger, a constant voltage charger, a constantcurrent/constant voltage charger, a delta-V charger, and/or the like,and/or a combination of these.

One suitable example of a rectifier and switch circuit 630 is describedin greater detail below with respect to FIG. 8.

The primary power interface 640 may be configured to couple the primarypower signal PRI_IN to the rectifier and switch circuit 630 via a powersignal PRI_PWR, for example, to power the communications interface 680,to charge the battery circuit 660, and/or the like. The primary powerinterface 640 may include a circuit breaker, line filter, surgeprotector, power meter, and/or the like. However, in one embodiment, theprimary power interface 640 may simply be a wire segment connecting theprimary power signal PRI_IN to the rectifier and switch circuit 630.

Likewise, the alternate power interface 650 may be configured to receivepower from an alternate energy source and couple the received power tothe rectifier and switch circuit 630 via power signal ALT_PWR. Forexample, the alternate power interface 650 may be configured to receiveDC power from a photovoltaic power source and/or a generator. As oneexample, the alternate power interface 650 may be interfaced to agenerator as discussed in further detail by U.S. patent application Ser.No. 12/170,675, entitled “CELL SITE POWER GENERATION,” filed on Jul. 10,2008. In other examples though, the alternate power interface 650 may beconfigured to receive power from virtually any power source, such asthose discussed above.

The alternate power interface 650 may include a circuit breaker, linefilter, surge protector, power meter, and/or the like. However, thealternate power interface 650 may simply be a wire segment connectingalternate power signal ALT_IN to the rectifier and switch circuit 630.

The battery circuit 660 is configured to store power provided by theprimary power interface 640 and/or the alternate power interface 650 inany number of batteries or other electrical energy storage devices(e.g., ultracapacitors, supercapacitors, other capacitors, inductors,etc.), which may be arranged in any combination of seriesconfigurations, parallel configurations, and/or series and parallelconfigurations. In one example, the battery circuit 660 includesmultiple strings of serially connected batteries. As illustrated, thebattery circuit 660 is coupled to the rectifier and switch circuit 630via a battery power signal BAT_PWR. The battery circuit 660 is alsocoupled to the power controller 610 via output/control signals BAT_CTLand status signals BAT_STAT.

In one example, the battery circuit 660 has at least one battery stringthat comprises four serially connected batteries that together form anegative 48 volt (“V”) string that has an approximate suitable floatvoltage of 54 V. In one implementation, the battery circuit 660comprises serially connected absorbed glass mat (“AGM”) batteries thatare sealed valve-regulated, such as the SBS-S series or VRLA batteriesavailable from Storage Battery Systems® Inc. In another implementation,the battery circuit 660 comprises serially connected carbon nanotube(“CNT”) batteries. However, other batteries and/or energy storagedevices such as other types of AGM batteries, gel cell batteries, otherdeep cycle batteries, flooded lead-acid batteries, nickel-metal-hydridebatteries, nickel-cadmium batteries, lithium-ion batteries,lithium-polymer batteries, alkaline batteries, capacitors, and/or thelike, may also be suitably employed.

In one implementation, the battery circuit 660 is configured to providetwo different output signals each having a different voltage. Forexample, the battery power signal BAT_PWR may comprise two differentbattery power signals that may be routed by the rectifier and circuitswitch 630 to power two different loads (e.g. two different subsystemsof the communications interface 680, such as a GSM subsystem and a UMTSsubsystem). For example, the battery power signal BAT_PWR may comprise aBAT_PWR_24 signal carrying a 24 V signal and a BAT_PWR_48 signalcarrying a negative 48 V signal. In such implementations, the batterycircuit 660 comprises at least one string of serially connectedbatteries having a native voltage (e.g., 24 V) and a doubling switchingcircuit (e.g., an H-bridge coupled to a capacitor, inductor or both)configured to produce an output that is approximately double the nativevoltage of the battery string (e.g., 48 V). Alternatively, the doublingswitching circuit may be implemented within the rectifier and switchcircuit 630. In these implementations, during a power failure, thenative voltage of the battery string may directly power those loads thatrequire a lower voltage power source (e.g., by providing a 24 V voltagesource to a GSM subsystem via a BAT_PWR_24 signal). In suchimplementations, during a power failure, the power controller 610 mayalso produce a higher (i.e., doubled) voltage output signal at an outputnode by instructing an H-bridge or similar switching circuit (viaoutput/control signals BAT_CTL and/or RECT_CTL) to up-convert thevoltage of the battery string by repeatedly coupling the output node (1)first, to a first end of the battery string, and (2) second, to theother end of the battery string (with the polarity reversed). Thedoubling switching circuit may further comprise a capacitor, inductor,and/or or other energy storage device to store energy and to smooth outthe doubled voltage.

For example, one string of multiple individual batteries that togetherproduce 24V at an output node may be doubled by the switching circuit toproduce 48V at a different output node. Such control of individualbattery strings may be implemented by the BAT_CTL signal from the powercontrol 610. In this way, for example, the power controller 610 mayprovide a (positive or negative) 24 V voltage source to legacy GSMsubsystems via a BAT_PWR_24 signal and a negative 48 V voltage source tonext-generation UMTS or LTE subsystems via a BAT_PWR_48 signal. In suchimplementations, due to a floating ground that is employed to facilitatethe voltage up-conversion, the two subsystems that utilize the twodifferent power signals must be electrically isolated. Since switchingcircuits such as H-bridges have relatively low losses, the conversionefficiency in such implementations may be higher than other systems thatutilize an inverter to perform DC-DC conversion.

The battery circuit 660 may additionally comprise one or moretemperature sensors configured to provide measured temperatures in ornear the battery circuit 660 to the power controller 610 via batterystatus signals BAT_STAT so that the power controller 610 may calculateor adjust operating, charging, or testing values and/or other parametersthat are temperature-dependent (e.g., the number of rectifiers tooperate, suitable float voltages, charging voltages or currents,estimated battery charge, etc.).

The communications interface 680 is configured to interface wirelessdevices to a back-haul 694 via an antenna 692. The communicationsinterface 680 typically includes both digital and RF electronics. In oneembodiment, the communications interface 680 includes an RF transceiverand digital control circuitry. However, other components may also beassociated with a transceiver and/or other circuits. The communicationsinterface 680 is powered from the rectifier and switch circuit 630 vialine LOAD_PWR and is configured to provide status signal COM_STAT toindicate an operational status such as failure of back-haul 694, thenumber of wireless devices associated with cell site 600, powerconsumption data, and/or the like.

Power Controller Examples

FIG. 7 is a block diagram of a power controller 710. The powercontroller 710 includes a processor 714, a battery circuit interface716, a rectifier and switch circuit interface 780, and an operation,management, and control (OMC) interface 720, and may be configured toreceive or provide control signals 712. The power controller 710 may beemployed as an embodiment of the power controller 610 of FIG. 6. Thepower controller 710 may also be employed in systems other than thesystems of FIGS. 1-6.

As illustrated, the processor 714 is configured to control theoperations of the rectifier and switch circuit 630, including selectiveswitching and testing of rectifiers, via a rectifier and switch circuitinterface 780 and control signals RECT_CTL. The processor 714 is alsoconfigured to receive rectifier status signals RECT_STAT. In addition,processor 714 may interface with the battery circuit 660 (e.g., viabattery circuit interface 716, battery status signals BAT_STAT, andbattery control signals BAT_CTL) to control the operations of thebattery circuit, including selective switching, charging, testing, andpower failure handling of battery strings within the battery circuit.The processor 714 is further configured to provide a status signal to aremote system (e.g., via OMC interface 720 and status signal STATUS).

The processor 714 is further configured to receive a configurationsignal CONFIG to represent a hardware configuration, to set variousthreshold levels, operational parameters, and/or the like. Any number ofconfiguration signals may be provided. In one embodiment, configurationsignals are employed to represent the number and/or types of rectifiersin the rectifier and switch circuit 630, the alternate power sourcecoupled to the alternate power interface 650, the number of batterystrings in the battery circuit 660, the types of batteries in thebattery circuit 660, the capacities of batteries in the battery circuit660, the desired output voltage at one or more nodes for the batterystrings, and/or the like. As another example, a configuration signal maybe provided to indicate the load capacity of the rectifiers in therectifier and switch circuit 630, so that the processor 714 may moreaccurately determine the number of active/online rectifiers needed toprovide efficient rectification.

As yet another example, a configuration signal is employed to set orestablish an applicable rotation policy or schedule that specifies a setof preferences, policies, schedules, procedures, and other informationregarding how the power controller 710 should perform the process 900 ofFIG. 9 for managing the rectifier and switch circuit 630. For example, aconfiguration signal may be employed to set various rotation policyparameters and/or indicate how the power controller 610 should calculatevarious rotation policy parameters, including: delta values; thresholdvalues; metrics used; a rectifier rotation or selection schedule,sequence, order, or strategy; turn on delays; turn off delays; thresholdtemperatures; current ranges; and/or testing times. The various rotationpolicy parameters and methods for selecting or calculating these policyparameters are described in greater detail herein with respect to FIG.9.

The configuration signal CONFIG may be provided from a switch (e.g., aDIP switch), pull-up resistors, pull-down resistors, jumpers, and/or thelike. Alternatively, similar configuration information may be read bythe processor 714 from a memory or be received from another processor.

The processor 714 is also configured to receive various status signalsand provide various control signals as illustrated in FIG. 7 in order tomanage and control the operation of the rectifier and switch circuit630. For example, status signals COM_STAT, RECT_STAT and BAT_STAT may beemployed to represent the status of the communications interface 680,the rectifier and switch circuit 630, and the battery circuit 660,respectively. The processor 714 may also provide control signalsRECT_CTL, which may further comprise three sets of multiple controlsignals described in greater detail herein, including RECT_CTL_STATEsignals to control the operational state (e.g., output voltage) ofrectifiers within the rectifier and switch circuit 630, RECT_CTL_SRCsignals to control which input power signal is rectified by therectifiers, and RECT_CTL_CPL signals to control which rectifiers arecoupled to a load. The various status signals and control signals aredescribed in additional detail with respect to FIGS. 6 and 8.

The processor 714 may be a microprocessor, a microcontroller, a digitalsignal processor (DSP), and/or the like. However, in other embodiments,digital logic, analog logic, combinations of digital logic and analoglogic, and/or the like may also be employed instead of a processor. Forexample, such embodiments may be implemented in a field-programmablegate array (FPGA), in an application-specific integrated circuit (ASIC),in other programmable logic devices (PLDs), and/or the like.

A rectifier and switch circuit interface 780 is configured to interfacethe processor 714 with the rectifier and switch circuit 630 of FIG. 6.For example, the rectifier and switch circuit interface 780 interfacesstatus signals RECT_STAT from the rectifier and switch circuit 630 tothe processor 714 (e.g., to sense the conditions of each rectifier inthe rectifier and switch circuit 630, such as output currents) andinterfaces the power controller 710 to rectifier control signalsRECT_CTL (e.g., to select which rectifiers in the rectifier and switchcircuit 630 are in active online operation). For example, the rectifierand switch circuit interface 780 may include multiplexers, drivers,buffers, logic gates, analog circuits, and/or other logic or circuitryto perform sampling, multiplexing, demultiplexing, conversion, and/orthe like. As one example, the rectifier and switch circuit interface 780includes an array of analog to digital converters (“ADCs”) that areconfigured to digitize each of the status signals RECT_STAT and driversconfigured to drive each of rectifier control signals RECT_CTL.

The battery circuit interface 716 is configured to interface theprocessor 714 with the battery circuit 660 of FIG. 6. For example, thebattery circuit interface 716 interfaces battery status signals BAT_STATfrom the battery circuit 660 to the processor 714 (e.g., to senseconditions of each battery string in the battery circuit 660) andinterfaces the power controller 710 to battery control signals BAT_CTL(e.g., to select which strings of the battery circuit 660 are coupled tothe rectifier and switch circuit 630). For example, the battery circuitinterface 716 may include multiplexers, drivers, buffers, logic gates,analog circuits, and/or other logic or circuitry to perform sampling,multiplexing, demultiplexing, conversion, and/or the like. As oneexample, the battery circuit interface 716 includes an array of ADCsthat are configured to digitize each of battery status signals BAT_STATand drivers configured to drive each of battery control signals BAT_CTL.

The OMC interface 720 is configured to interface the processor 714 to aremote system, and to provide operational data regarding the cell siteand/or the cell site power system to the remote system. The OMCinterface 720 may include drivers, buffers, inverters, logic gates,network interface units, multiplexers, and/or the like. Likewise, theOMC interface 720 may be configured to multiplex the status signalSTATUS onto the back-haul 694 or may provide the status signal STATUS asa discrete signal.

Example Rectifier and Switch Circuit

FIG. 8 is a schematic diagram of a portion of a suitable rectifier andswitch circuit 830, which may comprise multiple rectifiers 860,rectifier source switches 865, and rectifier load switches 870. Therectifier and switch circuit 830 may be employed as an embodiment of therectifier and switch circuit 630 of FIG. 6. The rectifier and switchcircuit 830 may also be employed in systems other than the systems ofFIGS. 1-6.

As illustrated, the rectifier and switch circuit 830 includes sixrectifiers 860A-F. Although six rectifiers are shown, two or morerectifiers 860 may be employed in the rectifier and switch circuit 830.Each rectifier is configured to rectify input power before providing itto a load. Each rectifier may be rated or otherwise configured toprovide a maximum output current (or “capacity”) and/or maximum outputvoltage. In some examples, the rectifiers each have a capacity betweenapproximately 30 Amps (“A”) and 40 A. The various rectifiers 860 mayhave different capacities; for example, the rectifier and switch circuit860 may comprise two 30 A rectifiers 860, two 40 A rectifiers 860, andtwo 50 A rectifiers 860. As previously described, the power controller610 may control the operational state of each of the rectifiers (e.g.,whether the rectifier is on/off, the output voltage, the output current,and other operational parameters) via control signals RECT_CTL_STATE(not shown in FIG. 7).

As shown, each rectifier 860 may be arranged in series with amulti-position rectifier source switch 865 that selectively couples therectifier 860 to one or more rectification input source signals, such asPRI_PWR or ALT_PWR. As shown, each rectifier source switch 865 iscontrolled by a control signal RECT_CTL_SRC (e.g., rectifier sourceswitch 865 A is controlled by the control signal RECT_CTL_SRC A). Eachrectifier 860 may also be arranged in series with a rectifier loadswitch 870 that selectively couples the rectifier 860 to a load lineLOAD_PWR. As shown, each rectifier load switch 870 is controlled by acontrol signal RECT_CTL_CPL (e.g., rectifier load switch 870A iscontrolled by the control signal RECT_CTL_CPL A). Rectifier sourceswitches 865 and rectifier load switches 870 may be implemented byswitching devices of any type (e.g., field-effect transistors, insulatedgate bipolar transistors, junction field-effect transistors,bipolar-junction transistors, relays, transmission gates, etc.). In someexamples, one or more rectifier source switches 865 and/or rectifierload switches 870 may be omitted so that a rectifier 860 is directly andcontinuously coupled to only a single input power signal and/or a singleload.

When a new rectifier 860 is deployed within the rectifier and switchcircuit 830, the power controller 610 may record the time and/or date ofdeployment in an index or other data structure that correlatesdeployment times, failure times, applicable warranty periods, serialnumbers, and/or other similar information. Alternatively, oradditionally, the power controller 610 may send this information to aremote monitoring location. In this way, the power controller 210, viaregular testing of the rectifiers 860, may detect when a rectifier 860failure indicates that a warranty remedy is available (e.g., a freereplacement rectifier, free service, a refund, etc.) and may take stepstowards claiming any warranty remedy (e.g., by notifying a remotemonitoring location of the warranty remedy and/or otherwise).

Example Process

FIG. 9 is a logical flow diagram of a suitable process 900 for managingthe rectifier and switch circuit 630 having multiple rectifiers 860. Forclarity, the process 900 is described below as being performed by thepower controller 610 of FIG. 6. However, the process 900 may also beperformed by the processor 714 of the power controller 710, anothercomponent of the cell site 100 or the cell site 200, or another remotecomponent (e.g., at a remote monitoring location).

The process 900 may also be performed by other processors, by othercomponents, or in other systems, whether or not such processors,components, or systems are described herein. The process 900 may also beembodied on processor and/or computer readable media such asnon-volatile memory, volatile memory, and/or the like. The flow diagramdoes not show all functions or exchanges of data, but instead itprovides an understanding of commands and data exchanged under thesystem. Those skilled in the relevant art will recognize that somefunctions or exchange of commands and data may be repeated, varied,omitted, or supplemented, and other (less important) aspects not shownmay be readily implemented.

Aspects of the invention may be stored or distributed on tangible ornon-transitory computer-readable media, including magnetically oroptically readable computer discs, hard-wired or preprogrammed chips(e.g., EEPROM semiconductor chips), nanotechnology memory, biologicalmemory, or other data storage media. Alternatively, computer implementedinstructions, data structures, screen displays, and other data underaspects of the invention may be distributed over the Internet or overother networks (including wireless networks), on a propagated signal ona propagation medium (e.g., an electromagnetic wave(s), a sound wave,etc.) over a period of time, or they may be provided on any analog ordigital network (packet switched, circuit switched, or other scheme).

In the process 900 of FIG. 9, the power controller 610 determines whenand how to rotate rectifiers 860 into and out of an online state andimplements the determined rotation. As described previously, during theprocess 900, the power controller 610 may utilize a rotation policy thatspecifies a set of preferences, policies, parameters, schedules,procedures, and other information. A rectifier 860 is “online” when itis both actively rectifying an input source and providing a desiredoutput voltage and current that powers a load; it is “offline” when itis not. During the process 900, the power controller 610, in accordancewith a rotation policy or schedule, may rotate rectifiers 860 in amanner that approximately balances or equalizes the cumulative runtimes(e.g., the total time spent in an online state) of the variousrectifiers. By balancing the runtimes, the process 900 may reduce themean time between failures for the rectifier and switch circuit 630,which may reduce maintenance calls and/or cell site 100 outages.Additionally, balancing the runtimes may promote a more even shelftemperature within the rectifier and switch circuit 630. Furthermore,during the process 900, the power controller 610 may rotate rectifiers860 in a manner that runs rectifiers close to their maximum outputcurrent (or “capacity”), since typical rectifiers rectify moreefficiently closer to their maximum output current. By running therectifiers closer to capacity and thus more efficiently, the rectifierand switch circuit 630 will consume less power and may produce lessheat, which in turn reduces the strain on cooling systems and reducesthe power needed to operate cooling systems at the cell site 100.

Typical cell sites 100 utilize an “N+1” approach to guard againstrectifier failures. In an “N+1” approach, the cell site 100 maintainsonline, at all times, the minimum number of rectifiers necessary toapproximately accommodate the load demand plus at least one sparerectifier. Thus the online rectifiers may operate less efficiently sincethey run well below capacity due to the online spare. The typicalapproach may result in extra heat (due in part to lower efficiencies)and unnecessary wear of the rectifiers. In contrast, the process 900 mayimplement an “N+0” approach that permits a cell site 100 to maintainonline only the minimum number of rectifiers necessary to approximatelyaccommodate the load demand, without keeping any spares online. Thebattery circuit 660 permits a cell site 100 to operate without an onlinespare, since the battery circuit 660 can temporarily power the load inthe event that an online rectifier fails during operation. For example,during short, peak periods of power demand (e.g., when the load powerdemand exceeds 105% of online rectifier capacity for less than fiveminutes), the battery circuit 660 may provide the needed excess power tothe load in parallel to the online rectifiers.

To illustrate the cost savings that may be realized by runningrectifiers more efficiently during the process 900, consider that if therectification efficiency of a rectifier and switch circuit 630 increasesfrom 80% efficiency to 90% efficiency, there should be at least a 10%power reduction realized, since less input current is required toproduce the same output current. Additionally, due to the improvedefficiencies, the heat generated by the rectifier and switch circuit 630may also drop by 50%, which reduces the power needed to cool the cellsite 100 via cooling systems such as air conditioning. Since as much as28% of the power used at a typical cell site 100 goes towards coolingsystems, the total power reduction realized may be much higher thansimply a 10% reduction in input currents.

Alternatively, when temperatures in the cell site 100 or battery circuit660 drop near the freezing point of the battery circuit 660 (or nearother undesirably low temperatures), during the process 900, the powercontroller 610 may rotate additional rectifiers 860 online so that theonline rectifiers run at a lower efficiency and thus produce more heatto keep the temperature of the battery circuit 660 or other componentsabove a freezing point.

During the process 900, the power controller may also test the variousrectifiers by determining, during periods when two or more rectifiersare online, whether the online rectifiers are demonstrating propercurrent balancing (e.g., that each is producing its proportionate shareof the current drawn by a load). Finally, by handling redundantrectifiers, the process 900 may permit a cell site 100 to continueoperating even if one or more rectifiers fail and may reduce the numberof maintenance or site visits needed to maintain the cell site 600.

The process 900 of FIG. 9 begins at block 910, where the powercontroller 610 monitors the current and/or power demand of the rectifierand switch circuit 630 load (e.g., the communication interface 680,cooling systems (not shown), the power controller 610, and/or thebattery circuit 660 loads), the temperature within and/or near the cellsite (including the temperature of the battery circuit 660) and/or thestate of the various rectifiers 860 (as determined by the status signalsRECT_STAT). To monitor the actual, present load demand, the powercontroller 610 may monitor the output currents and/or power provided bythe various online rectifiers 860 to the load and/or the outputcurrent/power provided by the battery circuit 660, if it is alsopowering the load in parallel to the rectifier and switch circuit 630.Alternatively or additionally, in order to determine the load demand,the power controller 610 may monitor the input current and/or powerdrawn by the load (e.g., by evaluating the status signal COM_STAT and/orother status signals). Additionally or alternatively, the powercontroller 610 may estimate or predict the present load demand based onhistorical information, e.g., historical load demand information thatcorrelates time, date, and/or environmental conditions (e.g., ambienttemperature) to an estimated or predicted load demand.

To monitor the temperature within the cell site 100, the powercontroller 610 may evaluate the status signals BAT_STAT to determine thetemperature at one or more locations in the battery circuit 660.Additionally or alternatively, the power controller 610 may utilizeother status signals, including COM_STAT, RECT_STAT, other status orsensor signals not shown (e.g., status signals from a thermostat orcooling system), and/or weather data or forecasts received from a remoteserver to determine the temperature at one or more points in or near thecell site 100. Additionally or alternatively, the power controller 610may evaluate various status or sensor signals to determine otherenvironmental conditions that might affect the operation of therectifier and switch circuit 630 (e.g., humidity, dew point).

At decision block 920, the power controller 610 determines whether theload demand, cell site 100 temperature, an applicable rotation policy, arectifier status and/or other suitable factors necessitate a change oradjustment to the number of rectifiers 860 that are online and/or anadjustment to which particular rectifiers are online. If the powercontroller 610 determines that these factors necessitate a rectifierchange, the process 900 proceeds to block 930, otherwise the process 900repeats starting at block 910.

Table 3, below, includes some examples of possible conditions atdecision block 920 that would necessitate a change or adjustment to thenumber of rectifiers 860 that are online and/or an adjustment to whichparticular rectifiers are online. These examples are described ingreater detail herein.

TABLE 3 Example conditions that necessitate a change to the onlinerectifiers. 1 A sustained increase in load demand indicates one or moreadditional or different rectifiers 860 should come online to provideadditional power capacity. 2 A sustained decrease in load demandindicates one or more rectifiers 860 should come offline to improveefficiency. 3 A rectifier rotation is mandated by a prescribed orcalculated rotation policy or schedule that aims to balance the runtimesof the various rectifiers and/or to facilitate rectifier testing. 4 Thetemperature in the battery circuit 660 necessitates a change in thenumber or type of rectifiers 860 that are operating online. 5 A failedor anomalous rectifier should be taken permanently or temporarilyoffline.

As a first example, at block 920 the power controller 610 may determinewhether a sustained increase in load demand indicates that it shouldbring one or more additional or different rectifiers 860 online toprovide additional power capacity. In some implementations, the powercontroller 610 may determine whether the load demand has increased in asustained fashion by evaluating whether the average load amperage duringa time window increased by a particular delta amount since a prior timewindow or whether the average load amperage during the time window hasexceeded a threshold value. Alternatively, or additionally, the powercontroller 610 may determine whether other metrics, such as the median,maximum, or minimum amperage observed over a time window or over amoving time window has increased by a particular delta amount orexceeded a threshold value.

The power controller 610 may set a difference or delta amount to apredetermined percentage of the maximum output current of an individualrectifier (e.g., 2 A, which is 5% of the capacity of a single 40 Arectifier) or the maximum total output current of all of the onlinerectifiers (e.g., 4 A, which is 5% of the capacity of two online 40 Arectifiers).

The power controller 610 may alternatively or additionally utilize athreshold value that is set to a predetermined percentage of the maximumtotal output current of all of the online rectifiers (e.g., 84 A, whichis 105% of the 80 A capacity of two online 40 A rectifiers), to anamperage value that corresponds to an estimated efficiency of therectifier and switch circuit 630 (e.g., to correspond to an estimated90% efficiency), and/or to a value that reflects the ability or capacityof the battery circuit 660 to provide supplementary power above themaximum output of the online rectifiers.

Although the power controller 610 has been described as evaluating theaverage amperage over a particular time window, in otherimplementations, the power controller 610 may use other metrics, such asthe median, maximum, or minimum amperage observed over a time window todetermine whether an increase in load demand necessitates the additionor substitution of rectifiers.

The power controller 610 sets or receives the length of the time windowused to calculate average load amperage (or other metrics) to apredetermined turn on delay value, which in some examples is chosen tobe between approximately 5 and 30 minutes, and in one implementation is25 minutes, although other delays are possible based on the specificconfiguration and needs at the cell site. The power controller 610 mayadditionally or alternatively adjust the turn on delay based on othersuitable factors, such as the present or predicted load demands, theability or capacity of the battery circuit 660 to provide power thatsupplements the output of the rectifier and switch circuit 630, the timeof day or date, what input power source is being rectified (e.g.,PRI_PWR or ALT_PWR), and/or other operational parameters or conditions.

If the power controller 610 determines that the load demand hasincreased in a sustained fashion, the power controller 610 may determinethe number of additional rectifiers it should bring online in order toensure that the rectifier and switch circuit 630 is supplying the loadwith sufficient operational power. The power controller 610 maydetermine the number of rectifiers to add based on the increase in loaddemand as determined by the power controller 610, the capacity andefficiency of the rectifiers, the time of day, date, battery circuittemperature, and/or any other suitable factors. As a first example, ifthe load demand increased by 2 A (5% of a 40 A rectifier capacity) andall the rectifiers 860 have equal capacity (40 A) and are operating atover 90%, the power controller 610 may determine that it should add oneadditional rectifier 860. Additionally or alternatively, the powercontroller 610 may determine whether it should substitute one or morerectifiers having a different capacity for one or more onlinerectifiers. As a second example, if a rectifier with a 40 A capacity iscurrently online, but the load has been drawing 45 A on a sustainedbasis, the power controller 610 may determine that it should take the 40A rectifier offline and bring an available 50 A rectifier online.

One having skill in the art will appreciate that if all rectifiers arecurrently online, the power controller 610 cannot add an additionalrectifier, despite a sustained increase in load demand.

As a second example, at block 920, the power controller 610 maydetermine whether a sustained decrease in load demand indicates that itshould take one or more rectifiers offline in order to improveefficiency by running each online rectifier closer to its maximumoutput. In some implementations, the power controller 610 may determinewhether load demand has decreased in a sustained fashion by evaluatingwhether the average load amperage during a time window decreased by aparticular delta amount since a prior time window, or whether theaverage amperage during the time window has fallen below a thresholdvalue. The power controller 610 may set a delta amount to apredetermined percentage of the maximum output current of an individualrectifier (e.g., 2 A, which is 5% of the capacity of a single 40 Arectifier) or the maximum total output current of all of the onlinerectifiers (e.g., 4 A, which is 5% of the capacity of two online 40 Arectifiers).

The power controller 610 may additionally or alternatively utilize athreshold value set to a predetermined percentage of a total outputcurrent or power of all of the online rectifiers (e.g., 95% of totalcapacity), to an amperage value that corresponds to an estimatedefficiency of the rectifier and switch circuit 630 (e.g., a value thatcorresponds to an estimated 90% efficiency), and/or to a value thatreflects the ability or capacity of the battery circuit 660 to providesupplementary power above the maximum output of the online rectifiers.

The power controller 610 may set the length of the time window used tocalculate average load amperage (or other metrics) to a predeterminedturn off delay value, which in some examples is chosen to be between 5and 30 minutes. The power controller 610 may additionally oralternatively adjust the turn off delay based on other suitable factors,such as those described previously as being suitable for adjusting aturn on delay.

If the power controller 610 determines that the load demand hasdecreased in a sustained fashion, the power controller 610 may determinethe number of currently online rectifiers that it should take offline.The power controller 610 may determine the number of rectifiers to takeoffline based on the decrease in load demand as determined by the powercontroller 610, the capacity of the rectifiers, the time of day, date,battery circuit temperature, and/or any other suitable factors. As afirst example, if the load demand decreased by 2 A (e.g., 5% of a 40 Arectifier) and all the rectifiers 860 have equal capacity (40 A), thepower controller 610 may determine that it should take one rectifieroffline. Additionally or alternatively, the power controller 610 maydetermine whether it should substitute one or more rectifiers with adifferent capacity for one or more online rectifiers in order to balancerectifiers to load to increase efficiency (e.g., to 90%). For example,if a rectifier with a 50 A capacity is currently online, but the loadhas drawn 35 A on a sustained basis, the power controller 610 maydetermine that it should take the 50 A rectifier offline and bring a 40A rectifier online.

One having skill in the art will appreciate that if only one rectifieris online and no smaller rectifiers are available, the power controller610 will typically not take the single rectifier offline, despite asustained decrease in load demand since it must continue to power theload in some fashion.

As a third example, at block 920, the power controller 610 may determinewhether, regardless of whether the load demand has changed, it shouldrotate one or more online rectifiers offline in accordance with anapplicable rotation policy or schedule that aims to balance or equalizethe runtimes of the various rectifiers and/or to facilitate rectifiertesting. For example, in accordance with an applicable rotation policy,the power controller 610 may rotate each rectifier offline after it hasprovided service online for one hour, four hours, a day, a week, etc.The online period used may depend on the number of rectifiers that aresuitable for online service (e.g., the period may be 24 hours divided bythe number of functional rectifiers).

Alternatively, or additionally, in accordance with an applicablerotation policy, the power controller 610 may evaluate informationrelating to the actual historical runtime of each rectifier 860 todetermine whether a rectifier rotation is needed to help balance theruntimes of the various rectifiers. For example, the power controller610 may evaluate a log reflecting when various rectifiers were online ortheir cumulative time online. For example, if a new rectifier wasrecently added to the rectifier and switch circuit 630, a rotationpolicy may dictate that it remain online for 3 hours at a stretch whileolder rectifiers remain online for only 1 hour until the cumulativeruntime of the new rectifier approximately matches the cumulativeruntime of the older rectifiers. As another example, if a new rectifier860 was recently added to the rectifier and switch circuit 630, arotation policy may dictate that for a certain number of rotation cycles(e.g., 1000 round-robin cycles as described herein), the new rectifieris the first rectifier turned on and the last one turned off and/or thenew rectifier otherwise has a higher duty cycle than the olderrectifiers.

As a fourth example, at block 920, the power controller 610 maydetermine that the temperature in the battery circuit 660 (or elsewherein the cell site 100 or its environment) necessitates a change in thenumber or type of rectifiers 860 that are operating online. For example,during cold weather, if the temperature in the battery circuit 660 dropsbelow a certain threshold (e.g., within 5 degrees of the freezingtemperature of the batteries in the battery circuit 660), the powercontroller 610 may determine that it should bring one or more additionalrectifiers 860 online to ensure that the online rectifiers run at alower efficiency and thus produce more heat to keep the batteries fromfreezing. As another example, when a cold spell ends, if the temperaturein the battery circuit 660 rises above a certain threshold (e.g., morethan 5 degrees above the freezing temperature of the batteries in thebattery circuit 660), the power controller 610 may determine that itshould take one or more rectifiers offline (unless the load demandnecessitates otherwise) to improve efficiency and obviate the need forair conditioning, heat exchangers, or similar cooling techniques.

As a fifth example, at block 920, the power controller 610 may determinethat it should take a failed or anomalous rectifier permanently ortemporarily offline. For example if the status signals RECT_STATindicate that an anomalous rectifier 860 is producing an unbalanced orunequal current when compared to other rectifiers, the power controller610 may determine that it should take the anomalous rectifier offlineand replace it with a fully functional rectifier.

These examples of conditions that might necessitate a change to theonline rectifiers are intended to be illustrative, not exhaustive. Insome examples, the power controller 610 may determine, in accordancewith an applicable rotation policy, that a combination of these exampleconditions also necessitates a change in the online rectifiers. Forexample, if load demand has dropped and the temperature has risen(and/or remained above a threshold), the power controller 610 maydetermine that it should reduce the number of online rectifiers toimprove efficiency and avert the need for power-intensiveair-conditioning or heat exchanging. As another example, if load demandhas risen and an online rectifier is due for a scheduled rotation out ofonline duty, the power controller 610 may determine that rotating in alarger rectifier may facilitate both higher capacity and the scheduledrotation. In some other examples, the power controller 610 may determinethat, in accordance with an applicable rotation policy, a combination ofthese example conditions has counteracting effects, which indicate thatthe power controller 610 should maintain the current arrangement ofonline rectifiers. For example, if the load demand has decreased in asustained fashion, but the temperature in the battery circuit 660 hasalso dropped precipitously, the power controller 610 may determine thatdespite lower rectification efficiencies, it should keep all of thecurrently online rectifiers on duty so that the batteries will notfreeze.

At block 930, the power controller 610 selects incoming rectifiers inaccordance with an applicable rotation policy. The power controller 610may select incoming rectifiers if it determines that it should addadditional or different rectifiers due to a sustained change (e.g.,increase) in load demand, an undesired decrease in temperature, anapplicable rotation policy, a rectifier failure and/or similar events.The power controller 610 may select the incoming rectifiers on the basisof any suitable factors including: past, present, and/or predictedfuture load demands, the capacity of various online and offlinerectifiers, the state or condition of various online and offlinerectifiers (e.g., whether a rectifier has failed testing), thetemperature and/or environmental conditions, the cumulative runtime ofthe various online and offline rectifiers, a predetermined or calculatedrotation policy or schedule, the age of the rectifiers, etc.

In one implementation, in accordance with an applicable rotation policy,the power controller 610 selects the incoming rectifiers so that itrotates the rectifiers on a first-on/first-off, round-robin basis, sothat during a single round-robin cycle, each rectifier is replaced byevery other rectifier at least once. Such an approach approximatelybalances the runtimes of the various rectifiers. It also permits eachrectifier to be tested or compared against each of the other rectifiersat least once during a handoff period. Such testing is described ingreater detail herein at block 960. Of course, other rotation cycles forrectifiers may be used.

As an example, if the power controller 610 has six functional andequally sized rectifiers (e.g. rectifiers 860A-860F) at its disposal, inaccordance with a round-robin rotation policy, during one day it may runrectifiers 860A-B during an early morning low-demand period, 860A-Dduring a mid-morning high-demand period, rectifiers 860C-D during amidday low-demand period, rectifiers 860C-F during an afternoonhigh-demand period, and rectifiers 860E-F during an evening low-demandperiod. In subsequent days, in accordance with the same rotation policy,the power controller 610 may incrementally shift the pairings and/orsequence utilized (e.g., first by one rectifier, then by two rectifiers,etc.) to ensure that each possible combination of incoming and outgoingrectifiers is utilized.

One having skill in the art will appreciate that many suitableround-robin selection techniques and algorithms may be utilized toaccomplish the same goals of testing and comparing rectifiers andapproximately balancing the runtimes.

Additionally or alternatively, in accordance with an applicable rotationpolicy, if the rectifier and switch circuit 630 has rectifiers 860 withdifferent capacities, the power controller 610 may select incomingrectifiers in order to adjust the capacities of the online rectifiersand optionally, to implement a round-robin rotation policy. For example,the rectifier and switch circuit 630 may have two 25 A rectifiers, two40 A rectifiers, and two 100 A rectifiers. In the example, the powercontroller 610 may determine that under the present load demands, a highrectification efficiency would be achieved by replacing a 100 A onlinerectifier with one 40 A rectifier and one 25 A rectifier. The powercontroller 610 may then determine which 40 A rectifier and 25 Arectifier are next scheduled for inward rotation under a round-robinpolicy. As another example, the power controller 610 may determine thatit needs to raise the temperature of the battery circuit 660 by fivedegrees to avert freezing the batteries. The power controller 610 maythen determine that given the present load demand (e.g., 50 A), itshould replace two 40 A rectifiers with a 100 A rectifier in order togenerate the heat necessary to raise the temperature accordingly.

In other implementations, the power controller 610 may select incomingrectifiers on a random or semi-random basis or another strategy that onaverage, distributes the runtime of the various rectifiers fairlyuniformly and/or permits the various rectifiers to be tested against oneanother.

At block 940, the power controller 610 selects outgoing rectifiers inaccordance with an applicable rotation policy. The power controller 610may select outgoing rectifiers if it determines that it should takecurrently online rectifiers offline due to a sustained change (e.g.,decrease) in load demand, an undesired increase in temperature, anapplicable rotation policy, rectifier failure and/or similar events. Thepower controller 610 may select the outgoing rectifiers on the basis ofany suitable factors including those discussed previously at block 930.The power controller 610 may select outgoing rectifiers in conjunctionwith selecting incoming rectifiers at block 930 using any of the methodsdescribed previously with respect to block 930. For example, the powercontroller 610 may select outgoing rectifiers to accomplish a rotationof the rectifiers on a first-on/first-off, round robin basis, to adjustthe capacities of the online rectifiers, or on a random or semi-randombasis.

At block 950, the power controller 610 brings the selected incomingrectifiers online. The power controller 610 may bring the selectedincoming rectifiers online by commanding the incoming rectifiers (via acontrol signal such as RECT_CTL_STATE), to turn on, wake up from a sleepor standby mode, and/or begin rectifying an input power signal to aparticular DC output voltage and/or particular output current and/or inaccordance with other selected output parameters. For example, the powercontroller 610 may command the incoming rectifiers to raise their outputvoltage to the level of the online rectifiers and to activate currentsharing alarms.

In some implementations, the power controller 610 may additionally oralternatively bring an incoming rectifier online by coupling theincoming rectifier to an input power source signal (e.g., PRI_PWR orALT_PWR) using a control signal such as RECT_CTL_SRC. In still otherimplementations, the power controller 610 may additionally oralternatively bring an incoming rectifier online by coupling theincoming rectifier to a load using a control signal such asRECT_CTL_CPL. In order track the runtimes of the rectifiers 860, atblock 950, the power controller 610 may also record and/or transmit(e.g., to a remote monitoring location) the approximate time that itbrings an incoming rectifier online.

At block 960, the power controller 610 determines how much current eachonline rectifier is providing to the load. The power controller 610typically determines the current provided by each of the onlinerectifiers, including those that the power controller 610 selected atblock 940 to come offline at block 970. The power controller 610 maymake this determination by evaluating status signals such as RECT_STATto determine the average amperage of each online rectifier during aparticular time window. Additionally or alternatively, the powercontroller 610 may determine other current metrics (e.g., peak current,median current, etc.) during the time window by evaluating statussignals. The power controller 610 may additionally store determinedcurrents and or other metrics in memory for later retrieval and/or sendthese values to a remote monitoring location (e.g., using the OMCinterface 720 to send the information via the status signal STATUS).

At block 960, the power controller 610 may additionally test the onlinerectifiers by comparing the currents provided by the various onlinerectifiers to determine if the currents are approximately balanced in anexpected manner. The expected current balance may depend on thespecifications and operational parameters of the online rectifiers. Forexample, if all of the online rectifiers are the same model andconfigured to operate in an identical fashion, the power controller 610may expect approximately equal currents from all of the onlinerectifiers and may thus verify whether the actual determined currentsare in fact roughly equal (e.g., all fall within a particular range,e.g., within 5% of each other). If the power controller 610 detects ananomalous current (e.g., a current that is lower or higher than anexpected value by a specified percentage or value), it may takeadditional steps, such as determining whether any of the onlinerectifiers have previously experienced an anomalous current (e.g., byaccessing previously stored values or querying a remote monitoringlocation), disabling or replacing the anomalous rectifier with another,storing the determined anomaly in memory, and/or reporting the anomalyto a remote monitoring location (e.g., using the OMC interface 720 tosend the information via the status signal STATUS).

By detecting and optionally recording current anomalies and/or runtimes,the power controller 610, other system components, or a remotemonitoring location may be able to determine whether a pattern ofrectifier failure emerges (e.g., whether a particular lot of rectifiersfails at unusually high rates and/or fails after very little active use)and/or whether warranty remedies (e.g., refunds or replacementrectifiers) are available.

The power controller 610 sets the length of the time window used atblock 960 to calculate average load amperage (or other metrics) to apredetermined or calculated testing time value, which in some examplesis approximately 1 minute. The power controller 610 may additionally oralternatively adjust the testing time value based on other suitablefactors, such as those described previously as being suitable forsetting a turn on delay value, the specifications of the variousrectifiers, and/or the operational settings of the various rectifiers.For example, the testing time value may be chosen so that all of theincoming rectifiers have an opportunity to reach a stable output afterstartup.

At block 970, the power controller 610 takes the selected outgoingrectifiers offline after the testing time has elapsed. The powercontroller 610 may also wait an additional amount of time beyond thetesting time, e.g., to ensure that the incoming rectifiers aredemonstrating expected currents that suggest they are functioning fullyand/or to correct or replace any non-functional incoming rectifiers. Thepower controller 610 may take the selected outgoing rectifiers offlineby commanding an outgoing rectifier to power off, to go into asleep/standby mode, to stop rectifying an incoming power signal, toreduce its output voltage to a much lower voltage than online rectifiers(e.g., 5 V lower than online rectifiers), to lower the maximum outputcurrent, and/or to turn off rectifier alarms (e.g., current sharingalarms) that produce a notification that currents are unbalanced, usinga control signal such as RECT_CTL_STATE. In some implementations, thepower controller 610 may additionally or alternatively take a selectedoutgoing rectifier offline by decoupling the outgoing rectifier from aninput power source signal (e.g., PRI_PWR or ALT_PWR) using a controlsignal such as RECT_CTL_SRC. In some implementations, the powercontroller 610 may additionally or alternatively take a selectedoutgoing rectifier offline by decoupling the outgoing rectifier from aload using a rectification control signal such as RECT_CTL LOAD. Inorder to permit tracking of the runtimes of the rectifiers, the powercontroller 610 may record and/or transmit (e.g., to a remote monitoringlocation) the approximate time that it takes an outgoing rectifieroffline.

After block 970, the power controller 610 repeats the process 900starting at block 910, by monitoring the load demand and temperature.

Although process 900 has been described as adjusting the configurationof online rectifiers “on the fly” or in real-time, one having skill inthe art will appreciate that the power controller 610 may insteadimplement a predetermined or programmed rotation that anticipatesforecasted or expected peak, average and low power demand periods. Insuch implementations, the battery circuit 660 may readily supplement theonline rectifiers as needed if unexpected peak periods occur.

CONCLUSION

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof means any connection or coupling,either direct or indirect, between two or more elements; the coupling orconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import, when used in this application, refer tothis application as a whole and not to any particular portions of thisapplication. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively. The word “or,” in reference to alist of two or more items, covers all of the following interpretationsof the word: any of the items in the list, all of the items in the list,and any combination of the items in the list.

The above Detailed Description of examples of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific examples for the invention are describedabove for illustrative purposes, various equivalent modifications arepossible within the scope of the invention, as those skilled in therelevant art will recognize. For example, while processes or blocks arepresented in a given order, alternative implementations may performroutines having steps, or employ systems having blocks, in a differentorder, and some processes or blocks may be deleted, moved, added,subdivided, combined, and/or modified to provide alternative orsubcombinations. Each of these processes or blocks may be implemented ina variety of different ways. Also, while processes or blocks are attimes shown as being performed in series, these processes or blocks mayinstead be performed or implemented in parallel, or may be performed atdifferent times. Further any specific numbers noted herein are onlyexamples: alternative implementations may employ differing values orranges.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various examples described above can be combined to providefurther implementations of the invention. Some alternativeimplementations of the invention may include not only additionalelements to those implementations noted above, but also may includefewer elements.

Any patents and applications and other references noted above, includingany that may be listed in accompanying filing papers, are incorporatedherein by reference. Aspects of the invention can be modified, ifnecessary, to employ the systems, functions, and concepts of the variousreferences described above to provide yet further implementations of theinvention.

These and other changes can be made to the invention in light of theabove Detailed Description. While the above description describescertain examples of the invention, and describes the best modecontemplated, no matter how detailed the above appears in text, theinvention can be practiced in many ways. Details of the system may varyconsiderably in its specific implementation, while still beingencompassed by the invention disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the invention should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific examplesdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed examples, but also allequivalent ways of practicing or implementing the invention under theclaims.

To reduce the number of claims, certain aspects of the invention arepresented below in certain claim forms, but the applicant contemplatesthe various aspects of the invention in any number of claim forms. Forexample, while only one aspect of the invention is recited as ameans-plus-function claim under 35 U.S.C. §112, ¶6, other aspects maylikewise be embodied as a means-plus-function claim, or in other forms,such as being embodied in a computer-readable medium. (Any claimsintended to be treated under 35 U.S.C. §112, ¶6 will begin with thewords “means for”, but use of the term “for” in any other context is notintended to invoke treatment under 35 U.S.C. §112, ¶6.) Accordingly, theapplicant reserves the right to pursue additional claims after filingthis application and to pursue such additional claim forms, in eitherthis application or in a continuing application.

I claim:
 1. A non-transitory computer-readable medium carryinginstructions that, when performed by a processor, perform a method forconserving power in a wireless communications system, the methodcomprising: detecting a reduced availability of a power source for thewireless communications system, wherein the wireless communicationssystem forms part of a wireless telecommunications network; monitoringcurrent drawn by the wireless communications system, wherein thewireless communications system has at least one online rectifier,wherein the at least one online rectifier rectifies an input source andprovides an output voltage and current to the wireless communicationssystem, wherein the wireless communications system has at least oneoffline rectifier, wherein the at least one offline rectifier does notrectify an input source and does not provide an output voltage andcurrent to the wireless communications system; selecting, in accordancewith a rotation policy or when detecting a reduced availability of thepower source, at least one rectifier to bring online or at least onerectifier to take offline; and switching, in accordance with therotation policy, at least one rectifier online or offline.
 2. Thenon-transitory computer-readable medium of claim 1, wherein the rotationpolicy includes taking one rectifier offline by determining whether asustained drawn current has decreased during a time window.
 3. Thenon-transitory computer-readable medium of claim 1, wherein the rotationpolicy prescribes a first on/first off round-robin rectifier rotation.4. The non-transitory computer-readable medium of claim 1, furthercomprising: determining whether the drawn current or the rotation policynecessitates a scheduled rectifier rotation that approximately balancesruntimes of the rectifier.
 5. The non-transitory computer-readablemedium of claim 1, further comprising: comparing the currents of onlinerectifiers to test the online rectifiers for failures.
 6. A powercontroller, comprising: a rectifier and switch circuit interface; anoperation, management, and control (OMC) interface; a processor; and amemory storing instructions that, when executed by the processor, causethe power controller to: detect, by receiving a signal from the OMCinterface, availability of a power source for a wireless communicationssystem, wherein the wireless communications system forms part of awireless telecommunications network; wherein the wireless communicationssystem has at least one online rectifier, wherein the at least oneonline rectifier rectifies an input source and provides an outputvoltage and current to the wireless communications system, wherein thewireless communications system has at least one offline rectifier, andwherein the at least one offline rectifier does not rectify an inputsource and does not provide an output voltage and current to thewireless communications system; select, in accordance with a rotationpolicy or when detecting a reduced availability of the power source, atleast one rectifier to bring online or at least one rectifier to takeoffline; and switch, in accordance with the rotation policy, theselected at least one rectifier from online to offline or offline toonline, wherein switching further comprises sending a request to therectifier and switch circuit interface, and wherein the request includesinstructions to switch the selected at least one rectifier from onlineto offline or offline to online.
 7. The power controller of claim 6,wherein the instructions when executed by the processor further causethe power controller to: receive, from the OMC interface, status signalsfor multiple rectifiers; and switch, by sending a switch signal to therectifier and switch circuit interface, at least one rectifier of themultiple rectifiers from online to offline based on the received statussignals.
 8. The power controller of claim 6, wherein the instructionswhen executed by the processor further cause the power controller to:monitor, by receiving another signal from the OMC interface, current andpower demand from multiple rectifiers associated with the wirelesscommunications network during a first period of time; store monitoredcurrent and power demand information; and based on the stored currentand power demand information, switch one or more of the multiplerectifiers from online to offline during a second period of time.
 9. Thepower controller of claim 6, wherein the instructions when executed bythe processor further cause the power controller to: determine whetherat least two online rectifiers are demonstrating current balancing; andsend an indication that the at least two online rectifiers aredemonstrating current balancing to a remote system.
 10. The powercontroller of claim 6, wherein the instructions when executed by theprocessor further cause the power controller to: receive temperatureinformation from sensors associated with the wireless communicationssystem; determine whether the temperature information indicates atemperature measurement for the wireless communications system hasexceeded a threshold temperature; and in response to determining thetemperature measurement has exceeded the threshold temperature, switchat least one rectifier to offline.
 11. The power controller of claim 6,wherein the instructions when executed by the processor further causethe power controller to: receive weather forecasting information; and inresponse to the received weather forecasting information, switch, inaccordance with the rotation policy, at least one rectifier online oroffline.
 12. The power controller of claim 6, wherein the rotationpolicy is based on at least one of following: a measured threshold valueof voltage or amps for each of the multiple rectifiers; a measuredtemperature threshold associated with batteries for the wirelesscommunications system; a rotation schedule; runtime for each of themultiple rectifiers; turn on or off delays for each of the multiplerectifiers; or any combination thereof.
 13. A method, comprising:monitoring an electrical load for each of multiple rectifiers configuredto power a wireless communications system, wherein at least one of themultiple rectifiers is online, wherein each online rectifier isconfigured to rectify an input source and provide an output voltage andcurrent to at least partially power the wireless communications system,wherein at least one of the multiple rectifiers is offline, wherein theat least one offline rectifier does not rectify an input source and doesnot provide an output voltage to the wireless communications system;selecting, in accordance with a rotation policy or when detecting areduced availability of the power source, at least one rectifier tobring online or at least one rectifier to take offline; and switching,in accordance with the rotation policy, at least one rectifier online oroffline.
 14. The method of claim 13, further comprising: monitoringtemperature near the multiple rectifiers; and switching, in accordancewith the rotation policy, at least one rectifier online or offline basedon a temperature change.
 15. The method of claim 13, wherein therotation policy is based on at least one the following: a measuredthreshold value of voltage or amps for each of the multiple rectifiers;a measured temperature threshold associated with batteries for thewireless communications system; a rotation schedule; runtime for each ofthe multiple rectifiers; turn on or off delays for each of the multiplerectifiers; or any combination thereof.
 16. The method of claim 13,further comprising: receiving weather forecasting information; and inresponse to the received weather forecasting information, switching, inaccordance with the rotation policy, at least one of the multiplerectifiers online or offline.
 17. The method of claim 13, furthercomprising: determining that one or more of the multiple rectifiers isreceiving a sustained increase in electrical load demand; and inresponse to determining the sustained increase, switching at least oneof the multiple rectifiers from offline to online.
 18. The method ofclaim 13, further comprising: receiving a notification that one of themultiple rectifiers has failed; in response to receiving thenotification, permanently switching the failed rectifier to offline; andsending an indication to an administrator of the wireless communicationssystem, wherein the indication includes identifying information for thefailed rectifier.
 19. The method of claim 13, further comprising:determining whether at least one of the multiple rectifiers is receivinga sustained decrease in electrical load demand; and in response todetermining the at least one of the multiple rectifiers is receiving asustained decrease in electrical load demand, switching the at least oneof the multiple rectifiers to offline.
 20. The method of claim 13,wherein the rotation policy includes a round-robin algorithm to rotateeach of the multiple rectifiers from online to offline.